Occlusion resistant catheter and method of use

ABSTRACT

An implantable occlusion and tissue ingrowth resistant fluid interface is provided with a housing, an orifice and a catheter port. The housing is formed from at least one biocompatible material and is configured without sharp edges or corners. The housing at least partially defines an internal housing cavity. The orifice member at least partially defines an orifice between the internal housing cavity and an exterior of the housing. The orifice has an elongated transverse cross-section configured with a length that is at least four times its maximum width. The catheter port is located on the housing and is configured to couple with a catheter such that the internal housing cavity is in fluid communication with a lumen of the catheter when the catheter is coupled to the catheter port. Embodiments having a moving cylinder, a rotor, and non-chemical surface modifications, as well as methods of use are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/216,530 filed Mar. 17, 2014 which claims the benefit under 35 U.S.C.119 of U.S. Provisional Patent Application 61/801,232 filed Mar. 15,2013, and entitled “Occlusion Resistant Catheter and Method of Use”,each of which is herein incorporated by reference in its entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD

The present disclosure relates to implantable occlusion resistant fluidinterfaces, such as catheter tips used in the treatment ofhydrocephalus.

BACKGROUND

One application of the occlusion resistant catheters disclosed herein isin shunting systems for cerebral-spinal fluid for use in treatinghydrocephalus. Conventional shunting systems used for this purposetypically include three components: a ventricular catheter portion; aperitoneal catheter portion; and a valve located between the twocatheter portions. The catheter portions typically are formed from aflexible synthetic polymer such as silicone rubber. A proximal end ofthe ventricular catheter portion is configured for insertion in acerebral ventricle. A distal end of the peritoneal catheter portion isconfigured for insertion in a body cavity, or in some cases configuredto drain fluid outside of the body. In many cases it would be preferablethat all three components be implanted subcutaneously and left in placefor many years.

The purpose of the shunting systems when treating hydrocephalus is toaffect periodic drainage of excess cerebral-spinal fluid from thecerebral ventricle. The cerebral ventricle that is typically drained isventricle III. The cerebral-spinal fluid is drained from the cerebralventricle in order to maintain proper endro-cranial tension or pressureat normal physiological values.

Conventional shunting systems for treating hydrocephalus suffer fromocclusion of the fluid path through the shunt, typically at the inlet inthe proximal end of the ventricular catheter portion and/or at theoutlet in the distal end of the peritoneal catheter portion. Manyattempts have been made to design clog resistant tips and orifices,however most have not met with much success. Blockage in the fluid pathtypically occurs as a result of tissue ingrowth and/or protein buildupin and around these orifices, often the result of the deposition offilaments of fibrin. Such blockage will often render the shuntingsystems useless in less than two years after implantation, requiringfrequent replacement of the shunt. Such replacement procedures can beexpensive, uncomfortable for the patient, and expose the patient tounnecessary complications associated with the procedures.

Further information relating to the treatment of hydrocephalus withconventional shunting systems may be found in U.S. Pat. No. 4,375,816 toLabianca and U.S. Pat. No. 7,582,068 to Koullick et al.

What is needed and is not provided by the prior art are implantableshunting systems that can be used in the treatment of hydrocephalus, andin other medical applications such as hemodialysis, without occlusionand tissue ingrowth.

SUMMARY OF THE DISCLOSURE

According to some aspects of the present disclosure, an implantableocclusion resistant fluid interface may be configured to preventinflammatory cells from binding to its surface(s), as the inflammatoryprocess and associated tissue can greatly reduce the necessary fluidflow of the implantable. In some embodiments, the occlusion resistantinterface is provided with a housing, an orifice and a catheter port.The housing is formed from at least one biocompatible material and maybe configured without sharp edges or corners. The housing may at leastpartially define an internal housing cavity. The orifice member isformed from at least one biocompatible material and may at leastpartially define an orifice between the internal housing cavity and anexterior of the housing. In some embodiments, the orifice has anelongated transverse cross-section configured with a length that is atleast four times its maximum width. The catheter port is located on thehousing and is configured to couple with a catheter such that theinternal housing cavity is in fluid communication with a lumen of thecatheter when the catheter is coupled to the catheter port.

In some embodiments, the maximum width of the transverse cross-sectionof the orifice does not exceed 0.003 inches. The orifice member may beconfigured to be movable with respect to the housing. In someembodiments, the movable orifice member includes a plate. The housingmay be formed from at least two separate pieces that are joined togetherto captivate the plate therebetween. In some embodiments, each of the atleast two separate pieces is an elongated hemispherical toroidal shellthat form a completed elongated toroidal shell when joined together. Theplate is located across a central aperture of the toroid in theseembodiments.

According to other aspects of the present disclosure, an implantableocclusion resistant shunt is provided with a fluid interface asdescribed above. The shunt is also provided with a flexible catheterformed from a biocompatible material. The catheter has a first end and asecond end, with the first end coupled with the catheter port of thefluid interface. In some embodiments, the shunt further comprises asecond fluid interface as described above. In these embodiments, thesecond end of the catheter is coupled with the catheter port of thesecond fluid interface.

According to other aspects of the present disclosure, a method oftreating hydrocephalus is disclosed. In some embodiments, the methodcomprises providing a shunt as described above, and implanting the fluidinterface and the first end of the shunt catheter within a patientadjacent to brain tissue. The method may also include implanting aremainder of the catheter within the patient, and locating the secondend of the catheter in a region of the patient away from the braintissue.

In some embodiments, an implantable occlusion resistant fluid interfacecomprises a housing, an orifice member and a catheter port. In theseembodiments, the housing is formed from at least one biocompatiblematerial and is configured without sharp edges or corners. The housingat least partially defines an internal housing cavity. The orificemember is also formed from at least one biocompatible material and it atleast partially defines an orifice between the internal housing cavityand an exterior of the housing. The orifice has an elongated transversecross-section configured with a maximum width and configured with alength that is at least four times the maximum width. The catheter portis located on the housing and is configured to couple with a cathetersuch that the internal housing cavity is in fluid communication with alumen of the catheter when coupled to the catheter port.

In some embodiments of the above fluid interface, the maximum width ofthe transverse cross-section of the orifice does not exceed 0.003inches. The orifice member may be movable with respect to the housingand may comprise a plate. The housing may be formed from at least twoseparate pieces that are joined together to captivate the platetherebetween. The at least two separate pieces may each be an elongatedhemispherical toroidal shell that form a completed elongated toroidalshell when joined together, and the plate may be located across acentral aperture of the toroid. In some embodiments, the orifice membercomprises nano-ripples formed by ion blasting on one or more surfaces.The nano-ripples may have a height of about 50 nm or less and a spacingof about 52 nm or less.

In some embodiments, an implantable occlusion resistant shunt comprisesa fluid interface as described above, and a flexible catheter formedfrom a biocompatible material. In these embodiments, the flexiblecatheter has a first end and a second end, and the first end is coupledwith the catheter port of the fluid interface. The shunt may furthercomprise a second fluid interface as described above, wherein the secondend of the catheter is coupled with the catheter port of the secondfluid interface.

In some embodiments, a method of treating hydrocephalus comprisesproviding a shunt as described above and implanting the fluid interfaceand the first end of the catheter within a patient adjacent to braintissue. These methods further comprise implanting a remainder of thecatheter within the patient and locating the second end of the catheterin a region of the patient away from the brain tissue.

In some embodiments, an implantable occlusion resistant fluid interfacecomprises a housing, an agitator and a catheter. In these embodiments,the housing is formed from at least one biocompatible material andconfigured without sharp edges or corners. The housing at leastpartially defines an internal housing cavity. The agitator is formedfrom at least one biocompatible material and at least partially definesan orifice between the internal housing cavity and an exterior of thehousing. The agitator is configured to passively move longitudinallybetween a first position and a second position, thereby changing fluidflow patterns within the internal housing cavity. The catheter port islocated on the housing and is configured to couple with a catheter suchthat the internal housing cavity is in fluid communication with a lumenof the catheter when coupled to the catheter port.

In some embodiments of the above fluid interface, the agitator iscylindrically shaped. The housing may comprise a transversecross-section that is generally triangular in shape. The transversecross-section may comprise three rounded apexes and three inwardlycurving side faces spanning between the three apexes. Each of the threeapexes may comprise a longitudinally extending internal channel thatoverlaps with and is in fluid communication with the internal housingcavity. Each of the three side faces may comprise an elongated slot influid communication with the internal housing cavity and with theexterior of the housing.

In some embodiments, an implantable occlusion resistant fluid interfacecomprises a housing, a rotor and a catheter port. In these embodiments,the housing is formed from at least one biocompatible material and isconfigured without sharp edges or corners. The housing at leastpartially defines an internal housing cavity. The rotor is formed fromat least one biocompatible material and is rotatably mounted within theinternal housing cavity such that a fluid flow in the cavity will causethe rotor to passively rotate. The catheter port is located on thehousing and is configured to couple with a catheter such that theinternal housing cavity is in fluid communication with a lumen of thecatheter when coupled to the catheter port.

In some embodiments of the above fluid interface, the rotor comprises aplurality of turbine blades. The rotor may be elongated and have twoends, and the fluid interface may further comprise a ball bearinglocated at each of the two rotor ends configured to allow the rotor topassively rotate relative to the housing. The ball bearings may be madeof sapphire. The housing may comprise an end cap having at least onevent hole therethrough. The vent hole may be configured to allow fluidto flow from the internal housing cavity, past the turbine blades andout through the vent hole to an exterior of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a side perspective view showing a first exemplary embodimentof an implantable fluid interface;

FIG. 2 is an exploded perspective view showing the components of thefluid interface of FIG. 1;

FIG. 3 is a cross-sectional view taken along Line 3-3 of FIG. 1;

FIG. 4 is an enlarged cross-sectional view showing a portion of FIG. 3;

FIG. 5 is a top plan view showing an exemplary fluid interface coupledwith a catheter;

FIG. 6 is a perspective view showing a second exemplary embodiment of animplantable fluid interface;

FIG. 7 is an exploded perspective view showing the components of thefluid interface of FIG. 6;

FIG. 8 is a cross-sectional view taken along Line 8-8 of FIG. 6;

FIG. 9 is a cross-sectional view taken along Line 9-9 of FIG. 6;

FIG. 10 is a perspective view showing a third exemplary embodiment of animplantable fluid interface;

FIG. 11 is an exploded perspective view showing the components of thefluid interface of FIG. 10;

FIG. 12 is another exploded perspective view taken from an oppositedirection from that of FIG. 11;

FIG. 13 is an enlarged perspective view of the middle housing portion ofthe fluid interface of FIG. 10;

FIG. 14 is a proximally-looking end elevation view of the middle housingportion of the fluid interface of FIG. 10; and

FIG. 15 is a cross-sectional view taken along Line 15-15 of FIG. 10.

DETAILED DESCRIPTION

Referring to FIGS. 1-3, a first exemplary embodiment of an implantableocclusion resistant fluid interface 10 is shown. In this embodiment,fluid interface 10 includes three components: a top housing shell 12, abottom housing shell 14, and a movable orifice member plate 16. In itsassembled configuration, as shown in FIG. 1, plate 16 is sandwichedbetween top shell 12 and bottom shell 14, and is movably captivatedtherebetween. In this embodiment, top shell 12 and bottom shell 14 aremanufactured to be identical pieces differing only in name.

Referring to FIG. 2, the main portion of bottom shell 14 is providedwith an oval shaped inner wall 18, a U-shaped outer wall 20, and arecessed portion 22 located therebetween. The right side of bottom shell14 is provided with a trough 24 that communicates with recessed portion22. Thickened wall sections 26 are provided on either side of trough 24.Top shell 12 includes the same features as bottom shell 14. During theassembly of device 10, the outer wall 20 of bottom shell 14 is joinedwith outer wall 20 of top shell 12, and the thickened wall sections 26of bottom shell 14 are joined with the thickened wall sections 26 of topshell 12. The joining process may include laser welding, ultrasonicwelding, adhesive, or other suitable joining processes. Once top shell12 is joined with bottom shelf 14, a catheter port 28 is formed at oneend of device 10 by troughs 24, as shown in FIG. 1.

Referring to FIG. 3, a cross-section of device 10 taken along line 3-3of FIG. 1 is shown. Once the top housing shell 12 and bottom housingshell 14 are joined together as previously described, their respectiverecessed portions 22 together form an internal housing cavity defined bythe toroidal housing of assembled device 10. As can be seen in FIG. 3,the inner walls 18 of top shell 12 and bottom shell 14 do not extend asfar towards the opposing shell as do outer walls 20. This arrangementleaves room for plate 16 to be movably received between top shell 12 andbottom shell 14 with additional space remaining above and/or below plate16 between it and inner walls 18 of top shell 12 and bottom shell 14.This additional space not only allows plate 16 to move relative to thehousing of device 10, but provides at least one oval shaped orifice 30(also shown in FIG. 1) between the internal housing cavity and theexterior of the housing (in the center portion of the toroidal housing).It can be seen from FIG. 3 that plate 16 is sized such that when itmoves laterally in either direction to contact the inside of outer walls20, the opposite side of plate 16 still remains within the space betweeninner walls 18. This is also true when plate 16 moves in eitherdirection longitudinally relative to top shell 12 and bottom shell 14.

Referring to FIG. 4, an enlarged portion of the cross-sectional view ofFIG. 3 showing plate 16 is provided. In this exemplary embodiment, plate16 is captivated between inner walls 18 of top housing shell 12 andbottom housing shell 14, and is allowed to float therebetween, as shownin FIGS. 3 and 4. As depicted in these figures, orifice 30 can existabove and/or below plate 30. It can be appreciated that a maximumorifice width W can be defined as the distance between the upper innerwalls 18 and lower inner walls 18 minus the thickness of plate 16. Thismaximum orifice width W would occur on the opposite side of plate 16when it rests against either the upper inner walls 18 or the lower innerwalls 18. In FIG. 4, plate 16 is depicted as being in a central positionwith an orifice width W/2 above the plate and another orifice havingwidth W/2 below the plate. Orifice or orifices 30 can also be defined ashaving a length of at least L, as shown in FIG. 4. The length L oforifice 30 can alternatively be defined in the longitudinal direction ofdevice 10, or even as the length of the inside circumference of innerwall 18 of either the top housing shell 12 or bottom housing shell 14.

In some embodiments, the maximum orifice width is maintained at about0.010 inches or less. In some embodiments, the maximum orifice width ismaintained at about 0.003 inches or less. In other embodiments, amixture of orifice sizes is used. Initial testing suggests that bykeeping the maximum orifice width W to these small dimensions, tissueingrowth and/or protein buildup that would otherwise clog orifice 30 canbe impeded or eliminated. To increase the flow rate through orifice 30,it is desirable for the orifice to have a larger cross-section. Theorifice cross-section is defined as being transverse to the fluid flowthrough the orifice. This can be accomplished by maintaining the orificewidth W at 0.010 inches, 0.003 inches or less and increasing the lengthL to create an elongated orifice. In some embodiments of theinventiveness fluid interface, the orifice has an elongated transversecross-section configured with a length that is at least four times themaximum width. In some embodiments, the orifice length is at least 10times the maximum width. In some embodiments the orifice length is atleast 100 times the maximum width. In the exemplary embodiment shown,the device is about 0.5 inches long, has an orifice length L of about0.7 inches (taken along the inside circumference of inner walls 18) anda maximum width W of 0.003 inches. This yields an orifice 30 having anelongated transverse cross-section configured with a length L that ismore than 200 times the maximum width W.

In addition to the elongated transverse cross-section of orifice 30, themovement of plate 16 relative to orifice or orifices 30 that itpartially defines contributes to impeding or eliminating tissue ingrowthand/or protein buildup that would otherwise clog the orifice(s). In somecases when device 10 is implanted within a patient, plate 16 iscontinuously or at least periodically moving relative to inner walls 18.Such movement can cause the orifice to be self-cleaning. The movementcan also create a varying orifice size, and therefore create variableregional fluid flow near the orifice. It is believed that such variableregional fluid flow, or flow instability, contributes to impeding oreliminating tissue and/or protein buildup in and around the orifice.Conversely, it is believed that a constant, non-varying fluid flowcontributes to tissue and/or protein buildup.

In some embodiments, top housing shell 12, bottom housing shell 14 andorifice member plate 16 are formed from titanium. The outside of device10 can be ultra-electropolished. To further inhibit orifice clogging,plate 16 can be nano-etched (roughened) to help prevent tissue andproteins from forming on plate 16. This can be accomplished with ionblasting, such as with a xenon ion gun, to form nano channels or rippleson plate 16. There will be less adsorbed proteins on the modifiedsurfaces due to a decrease of the surface energy caused by the surfacemodification. In some embodiments, the nano-ripples are less than about50 nm high. In some embodiments, the nano-ripples are about 10 nm high.Initial testing indicates that if the nano-ripples are created with aspacing of about 52 nm or less, adhesion of tissue and protein to plate16 can be prevented. Some embodiments include varied nano sized surfacecurvatures. These surface treatments can be applied to other surfaces ofdevice 10 and to surfaces of other devices disclosed herein.

In some embodiments, surface treatment(s) of plate 16 are purelymechanical, as described above, without any chemical treatments orchanges to the stoichiometry of the device surfaces. Advantages ofpurely mechanical treatments include avoidance of degradation of thematerial of plate 16, and also the avoidance of additional regulatoryissues, such as with the U.S. Food and Drug Administration (FDA).

As shown in FIG. 5, device 10 can be attached to one end of a catheter32. In one embodiment, this is accomplished by welding a titanium meshonto the neck or catheter port 28 of device 10, and then over moldingthe mesh with silicone to bond to catheter 32. Alternatively, a solidneck having one or more grooves 34, barbs or other recessed features maybe used as the core in an over molding process. A silicon materialhaving a higher durometer than the rest of the catheter 32 may beovermolded in the region of catheter port 28 as depicted in FIG. 5. Anessentially seamless transition 36 between the catheter 32 and catheterport 28 can be created by matching the outer diameter of catheter port28 with the outer diameter of catheter 32. This inhibits tissue ingrowthafter implantation and also enables device 10 to be removed from apatient without tissue damage.

A fluid interface device 10 constructed according to aspects of thepresent disclosure can be located at the inlet end of a catheter, at theoutlet end, or both, when the catheter is used to move fluid from oneregion of a patient to another.

The exterior surfaces of device 10 can be roughened to reduce surfacetension. This in turn can alleviate air bubbles from adhering to device10 during insertion of the device into the patient, which wouldotherwise cause adverse effects.

In an alternative embodiment (not shown), the principles of the presentdisclosure can be used to construct a device having a movable ballinstead of a movable plate. In such an embodiment, the ball canpartially define one or more orifices, such as round holes located onopposite sides of a housing.

Referring to FIGS. 6-9, a second exemplary embodiment of an implantableocclusion resistant fluid interface 100 is shown. In this embodiment,fluid interface 100 includes an elongated housing 102 and a cylindricalagitator 104 captivated within a central void 105 inside housing 102. Asbest seen in FIGS. 6 and 7, housing 102 comprises a proximal portion106, a middle portion 108, and a distal portion 110. Housing portions106, 108 and 110 may be separate components that are joined togetherduring assembly, or one or more of the components may be integrallyformed. Proximal housing portion 106 comprises a fitting configured tocouple to a catheter. A central lumen through proximal portion 106 is influid communication with central void 105 inside middle portion 108.Middle portion 108 is provided with three elongated slot 112 thatprovide fluid communication between central void 105 inside middleportion 108 and the exterior of device 100.

Referring to FIG. 8, middle housing portion 108 as a transversecross-section that is generally triangular in shape, but has roundedapexes and inwardly curving side faces. Each apex or lobe is providedwith a longitudinally extending channel 114 that overlaps with and is influid communication with central void 105. In some embodiments, agitator104 has a diameter of 0.059 inches and central void 105 has a diameterof 0.062 inches, leaving an even gap of about 0.0015 inches betweenagitator 104 and central void 105 on all sides, or a maximum gap ofabout 0.003 inches on one side. In some embodiments, channels 114 have adiameter of 0.032 inches.

As best seen in FIGS. 6 and 9, distal housing portion 110 is generallyhemispherical in shape and is contoured to mate smoothly with the apexesand inwardly curving side faces of middle housing portion 108.Similarly, proximal housing portion 106 has a larger cylindrical portionthat is also contoured to mate smoothly with the apexes and inwardlycurving side faces of middle housing portion 108. The outer diameter ofthe larger cylindrical portion of proximal housing portion 106 may beidentical to the outer diameter of the catheter it mates with. With theabove described contours and dimensions, device 100 may be more easilyimplanted and/or removed, and may reside within a patient withoutcausing trauma to adjacent tissue.

Referring to FIG. 9, a longitudinal cross-section of device 100 isshown. As can be seen, the length of agitator 104 is shorter than thelength of central void 105 so that agitator 104 may slide longitudinallywithin central void 105. With this arrangement, agitator 104 maypassively move within central void 105 when the orientation of device100 changes and or the direction of fluid flow through central void 105changes. For example, when the distal end 110 of device 100 is loweredand or fluid is flowing in a distal direction, agitator 104 may movedistally. Conversely, when the distal end 110 of device 100 is raisedand or fluid is flowing in a proximal direction, agitator 104 may moveproximally. Such changes in fluid direction may be caused by the use ofa fluid bulb in fluid communication with the catheter (not shown) toback flush the catheter system. Longitudinal movement of agitator 104may serve to disrupt any tissue ingrowth and or protein build up thatmay be starting to occur within device 100, and or may serve to changethe fluid flow paths when the fluid flow changes direction, therebyinhibiting tissue ingrowth and or protein build up.

In the exemplary embodiment shown in FIGS. 6-9, device 100 has anoverall length of about 0.65 inches and has a maximum diameter of about0.135 inches.

Referring to FIGS. 10-15, a third exemplary embodiment of an implantableocclusion resistant fluid interface 200 is shown. In this embodiment,fluid interface 200 includes a housing 202 and a rotor 204 (shown inFIG. 11) rotatably disposed within a central cavity 205 inside housing202. As best seen in FIGS. 11 and 12, housing 202 comprises a proximalportion 206, a middle portion 208, and a distal end cap 210. Housingportions 206, 208 and 210 may be separate components that are joinedtogether during assembly, or one or more of the components may beintegrally formed. Proximal housing portion 206 comprises adouble-barbed fitting configured to couple to a catheter. A centrallumen 212 through proximal portion 206 is in fluid communication throughapertures 214 with central void 205 inside middle portion 208.

Referring to FIG. 11, rotor 204 comprises a series of radially extendingturbine blades 216 disposed around its distal end. Rotor 204 is receivedwithin central cavity 205 inside middle housing portion 208 andcaptivated therein when distal cap 210 is attached to the distal end ofmiddle housing portion 208 during assembly. Rotor 204 is allowed tofreely rotate about a longitudinal axis by virtue of its being mountedbetween two ball bearings 218, which in some embodiments are made ofsapphire. The distal most ball 218 is located between a circular recess220 in the distal end of rotor 204 and a circular recess 222 on theproximal side of distal end cap 210 (shown in FIG. 12.) The proximalmost ball 218 is located between a circular recess 224 on the proximalend of rotor 204 (shown in FIG. 12) and a circular recess 226 locatedwithin middle housing portion 208 (shown in FIGS. 13 and 14.) The ventholes 228 are provided through distal end cap 210 to allow fluid to flowfrom central cavity 205 past turbine blades 216 and out through ventholes 228 to the exterior of device 200, and or along the same path inthe opposite direction. The flow of fluid past turbine blades 216 causesrotor 204 to rotate about its longitudinal axis. The distal most edgesof turbine blades 216 may be located very close to vent holes 228 (suchas within about 0.005 inches or less) such that the movement of turbineblades 216 disrupts tissue, protein and other matter from adhering toend cap 210.

Referring to FIG. 14, a longitudinal cross-section of device 200 isshown. Representative fluid flow is depicted with arrows between point Aand point B. Fluid flow may also be in the opposite direction.

In the exemplary embodiment shown in FIGS. 10-15, device 200 has anoverall length of about 0.54 inches and has a maximum diameter of about0.125 inches.

According to aspects of the invention, clog-resistant fluid orifices maybe formed between a passively movable component and a device housing,wherein the movable component is not part of a valve or other structure.In some embodiments, components forming an orifice, such as a movablecomponent and a housing, may comprise dissimilar metals. The dissimilarmetals can create an electrical potential between the components thatchanges the hydrophobicity of the surface(s). This in turn can repelproteins and or inhibit tissue ingrowth. In some embodiments, theelectrical potential is tuned to attract particular biomarkers that thedevice is configured to sample.

According to aspects of the invention, the exemplary fluid interfacedevices disclosed herein can be used in various applications. Forexample, the devices may be used in hydrocephalus drainage systems (suchas for brain injuries), in hemodialysis systems, in fluid samplingsystems, in wound care (such as for Extremity Compartment Syndrome,reconstructive flaps, burns, surgical incisions, etc.) The devices mayalso be used for drug delivery, such as long-term chemotherapeutics,localized drug delivery to tumor sites, delivery of antibiotics, painmedications, regenerative growth factors, etc. In some applications suchas hydrocephalus drainage systems, typical fluid flow rates can bearound 2 milliliters per minute or less. In other applications, fluidflow rates may be about 40 ml/min. unassisted and 400 ml/min. underassistance, such as suction or pressure.

As for additional details pertinent to the present invention, materialsand manufacturing techniques may be employed as within the level ofthose with skill in the relevant art. The same may hold true withrespect to method-based aspects of the invention in terms of additionalacts commonly or logically employed. Also, it is contemplated that anyoptional feature of the inventive variations described may be set forthand claimed independently, or in combination with any one or more of thefeatures described herein. Likewise, reference to a singular item,includes the possibility that there are plural of the same itemspresent. More specifically, as used herein and in the appended claims,the singular forms “a,” “and,” “said,” and “the” include pluralreferents unless the context clearly dictates otherwise. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Unless defined otherwise herein, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. The breadth of the present invention is not to be limited bythe subject specification, but rather only by the plain meaning of theclaim terms employed.

What is claimed is:
 1. An implantable occlusion resistant fluidinterface comprising: a housing formed from at least one biocompatiblematerial and configured without sharp edges or corners, the housing atleast partially defining an internal housing cavity; an agitator formedfrom at least one biocompatible material and at least partially definingan orifice between the internal housing cavity and an exterior of thehousing, the agitator configured to passively move longitudinallybetween a first position and a second position, thereby changing fluidflow patterns within the internal housing cavity; and a catheter portlocated on the housing and configured to couple with a catheter suchthat the internal housing cavity is in fluid communication with a lumenof the catheter when coupled to the catheter port.
 2. The fluidinterface of claim 1, wherein the agitator is cylindrically shaped. 3.The fluid interface of claim 1, wherein the housing comprises atransverse cross-section that is generally triangular in shape.
 4. Thefluid interface of claim 3, wherein the transverse cross-sectioncomprises three rounded apexes and three inwardly curving side facesspanning between the three apexes.
 5. The fluid interface of claim 4,wherein each of the three apexes comprises a longitudinally extendinginternal channel that overlaps with and is in fluid communication withthe internal housing cavity.
 6. The fluid interface of claim 4, whereineach of the three side faces comprises an elongated slot in fluidcommunication with the internal housing cavity and with the exterior ofthe housing.
 7. An implantable occlusion resistant fluid interfacecomprising: a housing formed from at least one biocompatible materialand configured without sharp edges or corners, the housing at leastpartially defining an internal housing cavity; a rotor formed from atleast one biocompatible material rotatably mounted within the internalhousing cavity such that a fluid flow in the cavity will cause the rotorto passively rotate; and a catheter port located on the housing andconfigured to couple with a catheter such that the internal housingcavity is in fluid communication with a lumen of the catheter whencoupled to the catheter port.
 8. The fluid interface of claim 7, whereinthe rotor comprises a plurality of turbine blades.
 9. The fluidinterface of claim 7, wherein the rotor is elongated and has two ends,and wherein the fluid interface further comprises a ball bearing locatedat each of the two rotor ends configured to allow the rotor to passivelyrotate relative to the housing.
 10. The fluid interface of claim 9,wherein the ball bearings are made of sapphire.
 11. The fluid interfaceof claim 8, wherein the housing comprises an end cap having at least onevent hole therethrough, the vent hole being configured to allow fluid toflow from the internal housing cavity, past the turbine blades and outthrough the vent hole to an exterior of the housing.